SOLUTION: if the average of six numbers is 18 and the average of three of the numbers is 15 then what is the sum of the remaining three numbers

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Question 215682: if the average of six numbers is 18 and the average of three of the numbers is 15 then what is the sum of the remaining three numbers
Answer by drj(1380) About Me  (Show Source):
You can put this solution on YOUR website!
If the average of six numbers is 18 and the average of three of the numbers is 15 then what is the sum of the remaining three numbers.

Step 1. Let y=3x be the sum of the remaining numbers where x is the average of the three numbers.

Step 2. Let 3*15 be the sum of the other three numbers or 45.

Step 3. 18=(45+y)/6 since the average of six numbers is 18 and the average of three of the numbers is 15. Solving for y yields the following steps:

18=%2845%2By%29%2F6

Multiply by 6 to both sides of the equation to get rid of denominator.

18%2A6=45%2By

108=45%2By

Subtract 45 from both sides of the equation

108-45=45%2By-45

y=63

Step 4. ANSWER: The average of the remaining three numbers is 63.

I hope the above steps were helpful.

For free Step-By-Step Videos on Introduction to Algebra, please visit http://www.FreedomUniversity.TV/courses/IntroAlgebra or for Trigonometry visit http://www.FreedomUniversity.TV/courses/Trigonometry.

And good luck in your studies!

Respectfully,
Dr J